Decorating the Boundaries
A wall is usually decorated with a single color of paint unless the wall is being shared and different paints are being used to demarcate the boundaries between the two portions. The selection of two paints should be made to enhance the beauty and not just dull the surrounding environment.
The color choice matters as it impacts the overall environment. Just like in this instance, the space has been painted with to extremely different colors that are in contrast with each other. The left side exhibits a purple tone while the right one a dull yellow tone. This distinction seems like a compromise.